Analyzing Leaky Waveguide Modes by Pseudospectral Modal Method

Leaky modes are important when optical waveguides fail to confine light completely. Computing waveguide modes to high accuracy is challenging if the waveguide has high index-contrast and sharp corners. The propagation constant of a leaky mode is complex, its imaginary part is an important physical quantity (the decay rate along the waveguide axis). To find complex propagation constants with a small imaginary part, high-accuracy numerical solutions are necessary. The pseudospectral modal method (PSMM), originally developed for diffraction gratings, has recently been reformulated as a full-vectorial waveguide mode solver. In this letter, the PSMM is extended to analyze two challenging waveguide benchmark problems involving leaky modes.